/*
* linux/drivers/video/fbcvt.c - VESA(TM) Coordinated Video Timings
*
* Copyright (C) 2005 Antonino Daplas <adaplas@pol.net>
*
* Based from the VESA(TM) Coordinated Video Timing Generator by
* Graham Loveridge April 9, 2003 available at
* http://www.vesa.org/public/CVT/CVTd6r1.xls
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of this archive
* for more details.
*
*/
#include <linux/fb.h>
#define FB_CVT_CELLSIZE 8
#define FB_CVT_GTF_C 40
#define FB_CVT_GTF_J 20
#define FB_CVT_GTF_K 128
#define FB_CVT_GTF_M 600
#define FB_CVT_MIN_VSYNC_BP 550
#define FB_CVT_MIN_VPORCH 3
#define FB_CVT_MIN_BPORCH 6
#define FB_CVT_RB_MIN_VBLANK 460
#define FB_CVT_RB_HBLANK 160
#define FB_CVT_RB_V_FPORCH 3
#define FB_CVT_FLAG_REDUCED_BLANK 1
#define FB_CVT_FLAG_MARGINS 2
#define FB_CVT_FLAG_INTERLACED 4
struct fb_cvt_data {
u32 xres;
u32 yres;
u32 refresh;
u32 f_refresh;
u32 pixclock;
u32 hperiod;
u32 hblank;
u32 hfreq;
u32 htotal;
u32 vtotal;
u32 vsync;
u32 hsync;
u32 h_front_porch;
u32 h_back_porch;
u32 v_front_porch;
u32 v_back_porch;
u32 h_margin;
u32 v_margin;
u32 interlace;
u32 aspect_ratio;
u32 active_pixels;
u32 flags;
u32 status;
};
static int fb_cvt_vbi_tab[] = {
4, /* 4:3 */
5, /* 16:9 */
6, /* 16:10 */
7, /* 5:4 */
7, /* 15:9 */
8, /* reserved */
9, /* reserved */
10 /* custom */
};
/* returns hperiod * 1000 */
static u32 fb_cvt_hperiod(struct fb_cvt_data *cvt)
{
u32 num = 1000000000/cvt->f_refresh;
u32 den;
if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK) {
num -= FB_CVT_RB_MIN_VBLANK * 1000;
den = 2 * (cvt->yres/cvt->interlace + 2 * cvt->v_margin);
} else {
num -= FB_CVT_MIN_VSYNC_BP * 1000;
den = 2 * (cvt->yres/cvt->interlace + cvt->v_margin * 2
+ FB_CVT_MIN_VPORCH + cvt->interlace/2);
}
return 2 * (num/den);
}
/* returns ideal duty cycle * 1000 */
static u32 fb_cvt_ideal_duty_cycle(struct fb_cvt_data *cvt)
{
u32 c_prime = (FB_CVT_GTF_C - FB_CVT_GTF_J) *
(FB_CVT_GTF_K) + 256 * FB_CVT_GTF_J;
u32 m_prime = (FB_CVT_GTF_K * FB_CVT_GTF_M);
u32 h_period_est = cvt->hperiod;
return (1000 * c_prime - ((m_prime * h_period_est)/1000))/256;
}
static u32 fb_cvt_hblank(struct fb_cvt_data *cvt)
{
u32 hblank = 0;
if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
hblank = FB_CVT_RB_HBLANK;
else {
u32 ideal_duty_cycle = fb_cvt_ideal_duty_cycle(cvt);
u32 active_pixels = cvt->active_pixels;
if (ideal_duty_cycle < 20000)
hblank = (active_pixels * 20000)/
(100000 - 20000);
else {
hblank = (active_pixels * ideal_duty_cycle)/
(100000 - ideal_duty_cycle);
}
}
hblank &= ~((2 * FB_CVT_CELLSIZE) - 1);
return hblank;
}
static u32 fb_cvt_hsync(struct fb_cvt_data *cvt)
{
u32 hsync;
if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
hsync = 32;
else
hsync = (FB_CVT_CELLSIZE * cvt->htotal)/100;
hsync &= ~(FB_CVT_CELLSIZE - 1);
return hsync;
}
static u32 fb_cvt_vbi_lines(struct fb_cvt_data *cvt)
{
u32 vbi_lines, min_vbi_lines, act_vbi_lines;
if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK) {
vbi_lines = (1000 * FB_CVT_RB_MIN_VBLANK)/cvt->hperiod + 1;
min_vbi_lines = FB_CVT_RB_V_FPORCH + cvt->vsync +
FB_CVT_MIN_BPORCH;
} else {
vbi_lines = (FB_CVT_MIN_VSYNC_BP * 1000)/cvt->hperiod + 1 +
FB_CVT_MIN_VPORCH;
min_vbi_lines = cvt->vsync + FB_CVT_MIN_BPORCH +
FB_CVT_MIN_VPORCH;
}
if (vbi_lines < min_vbi_lines)
act_vbi_lines = min_vbi_lines;
else
act_vbi_lines = vbi_lines;
return act_vbi_lines;
}
static u32 fb_cvt_vtotal(struct fb_cvt_data *cvt)
{
u32 vtotal = cvt->yres/cvt->interlace;
vtotal += 2 * cvt->v_margin + cvt->interlace/2 + fb_cvt_vbi_lines(cvt);
vtotal |= cvt->interlace/2;
return vtotal;
}
static u32 fb_cvt_pixclock(struct fb_cvt_data *cvt)
{
u32 pixclock;
if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
pixclock = (cvt->f_refresh * cvt->vtotal * cvt->htotal)/1000;
else
pixclock = (cvt->htotal * 1000000)/cvt->hperiod;
pixclock /= 250;
pixclock *= 250;
pixclock *= 1000;
return pixclock;
}
static u32 fb_cvt_aspect_ratio(struct fb_cvt_data *cvt)
{
u32 xres = cvt->xres;
u32 yres = cvt->yres;
u32 aspect = -1;
if (xres == (yres * 4)/3 && !((yres * 4) % 3))
aspect = 0;
else if (xres == (yres * 16)/9 && !((yres * 16) % 9))
aspect = 1;
else if (xres == (yres * 16)/10 && !((yres * 16) % 10))
aspect = 2;
else if (xres == (yres * 5)/4 && !((yres * 5) % 4))
aspect = 3;
else if (xres == (yres * 15)/9 && !((yres * 15) % 9))
aspect = 4;
else {
printk(KERN_INFO "fbcvt: Aspect ratio not CVT "
"standard\n");
aspect = 7;
cvt->status = 1;
}
return aspect;
}
static void fb_cvt_print_name(struct fb_cvt_data *cvt)
{
u32 pixcount, pixcount_mod;
int cnt = 255, offset = 0, read = 0;
u8 *buf = kmalloc(256, GFP_KERNEL);
if (!buf)
return;
memset(buf, 0, 256);
pixcount = (cvt->xres * (cvt->yres/cvt->interlace))/1000000;
pixcount_mod = (cvt->xres * (cvt->yres/cvt->interlace)) % 1000000;
pixcount_mod /= 1000;
read = snprintf(buf+offset, cnt, "fbcvt: %dx%d@%d: CVT Name - ",
cvt->xres, cvt->yres, cvt->refresh);
offset += read;
cnt -= read;
if (cvt->status)
snprintf(buf+offset, cnt, "Not a CVT standard - %d.%03d Mega "
"Pixel Image\n", pixcount, pixcount_mod);
else {
if (pixcount) {
read = snprintf(buf+offset, cnt, "%d", pixcount);
cnt -= read;
offset += read;
}
read = snprintf(buf+offset, cnt, ".%03dM", pixcount_mod);
cnt -= read;
offset += read;
if (cvt->aspect_ratio == 0)
read = snprintf(buf+offset, cnt, "3");
else if (cvt->aspect_ratio == 3)
read = snprintf(buf+offset, cnt, "4");
else if (cvt->aspect_ratio == 1 || cvt->aspect_ratio == 4)
read = snprintf(buf+offset, cnt, "9");
else if (cvt->aspect_ratio == 2)
read = snprintf(buf+offset, cnt, "A");
else
read = 0;
cnt -= read;
offset += read;
if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK) {
read = snprintf(buf+offset, cnt, "-R");
cnt -= read;
offset += read;
}
}
printk(KERN_INFO "%s\n", buf);
kfree(buf);
}
static void fb_cvt_convert_to_mode(struct fb_cvt_data *cvt,
struct fb_videomode *mode)
{
mode->refresh = cvt->f_refresh;
mode->pixclock = KHZ2PICOS(cvt->pixclock/1000);
mode->left_margin = cvt->h_front_porch;
mode->right_margin = cvt->h_back_porch;
mode->hsync_len = cvt->hsync;
mode->upper_margin = cvt->v_front_porch;
mode->lower_margin = cvt->v_back_porch;
mode->vsync_len = cvt->vsync;
mode->sync &= ~(FB_SYNC_HOR_HIGH_ACT | FB_SYNC_VERT_HIGH_ACT);
if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
mode->sync |= FB_SYNC_HOR_HIGH_ACT;
else
mode->sync |= FB_SYNC_VERT_HIGH_ACT;
}
/*
* fb_find_mode_cvt - calculate mode using VESA(TM) CVT
* @mode: pointer to fb_videomode; xres, yres, refresh and vmode must be
* pre-filled with the desired values
* @margins: add margin to calculation (1.8% of xres and yres)
* @rb: compute with reduced blanking (for flatpanels)
*
* RETURNS:
* 0 for success
* @mode is filled with computed values. If interlaced, the refresh field
* will be filled with the field rate (2x the frame rate)
*
* DESCRIPTION:
* Computes video timings using VESA(TM) Coordinated Video Timings
*/
int fb_find_mode_cvt(struct fb_videomode *mode, int margins, int rb)
{
struct fb_cvt_data cvt;
memset(&cvt, 0, sizeof(cvt));
if (margins)
cvt.flags |= FB_CVT_FLAG_MARGINS;
if (rb)
cvt.flags |= FB_CVT_FLAG_REDUCED_BLANK;
if (mode->vmode & FB_VMODE_INTERLACED)
cvt.flags |= FB_CVT_FLAG_INTERLACED;
cvt.xres = mode->xres;
cvt.yres = mode->yres;
cvt.refresh = mode->refresh;
cvt.f_refresh = cvt.refresh;
cvt.interlace = 1;
if (!cvt.xres || !cvt.yres || !cvt.refresh) {
printk(KERN_INFO "fbcvt: Invalid input parameters\n");
return 1;
}
if (!(cvt.refresh == 50 || cvt.refresh == 60 || cvt.refresh == 70 ||
cvt.refresh == 85)) {
printk(KERN_INFO "fbcvt: Refresh rate not CVT "
"standard\n");
cvt.status = 1;
}
cvt.xres &= ~(FB_CVT_CELLSIZE - 1);
if (cvt.flags & FB_CVT_FLAG_INTERLACED) {
cvt.interlace = 2;
cvt.f_refresh *= 2;
}
if (cvt.flags & FB_CVT_FLAG_REDUCED_BLANK) {
if (cvt.refresh != 60) {
printk(KERN_INFO "fbcvt: 60Hz refresh rate "
"advised for reduced blanking\n");
cvt.status = 1;
}
}
if (cvt.flags & FB_CVT_FLAG_MARGINS) {
cvt.h_margin = (cvt.xres * 18)/1000;
cvt.h_margin &= ~(FB_CVT_CELLSIZE - 1);
cvt.v_margin = ((cvt.yres/cvt.interlace)* 18)/1000;
}
cvt.aspect_ratio = fb_cvt_aspect_ratio(&cvt);
cvt.active_pixels = cvt.xres + 2 * cvt.h_margin;
cvt.hperiod = fb_cvt_hperiod(&cvt);
cvt.vsync = fb_cvt_vbi_tab[cvt.aspect_ratio];
cvt.vtotal = fb_cvt_vtotal(&cvt);
cvt.hblank = fb_cvt_hblank(&cvt);
cvt.htotal = cvt.active_pixels + cvt.hblank;
cvt.hsync = fb_cvt_hsync(&cvt);
cvt.pixclock = fb_cvt_pixclock(&cvt);
cvt.hfreq = cvt.pixclock/cvt.htotal;
cvt.h_back_porch = cvt.hblank/2 + cvt.h_margin;
cvt.h_front_porch = cvt.hblank - cvt.hsync - cvt.h_back_porch +
2 * cvt.h_margin;
cvt.v_back_porch = 3 + cvt.v_margin;
cvt.v_front_porch = cvt.vtotal - cvt.yres/cvt.interlace -
cvt.v_back_porch - cvt.vsync;
fb_cvt_print_name(&cvt);
fb_cvt_convert_to_mode(&cvt, mode);
return 0;
}
EXPORT_SYMBOL(fb_find_mode_cvt);
